KR101648341B1 - Method for manufacturing propylene glycol from glycerol and catalyst used therein - Google Patents

Abstract

The present invention relates to a process for producing a NiO-CuO / SiO ₂ nanocomposite catalyst from a Ni precursor compound, a Cu precursor compound, and SiO ₂ by a sol-gel method and to produce propylene glycol by hydrogenolysis of glycerol in the presence of the prepared catalyst Lt; / RTI > Using the catalyst according to the present invention, not only a high glycerol conversion and a high propylene glycol selectivity can be achieved at a low hydrogen / glycerol ratio of 10 or less, but also a high yield of propylene glycol can be produced over a long period of time.

Description

METHOD FOR MANUFACTURING PROPYLENE GLYCOL FROM GLYCEROL AND CATALYST USED THEREIN BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing propylene glycol by hydrogenation of glycerol,

The present invention relates to a process for preparing propylene glycol by hydrocracking of glycerol and a catalyst for the same, and more particularly to a process for producing propylene glycol by hydrogenolysis of glycerol with hydrogen in the presence of a NiO-CuO / SiO ₂ nanocomposite catalyst. And a NiO-CuO / SiO ₂ nanocomposite catalyst therefor.

Recently, biodiesel has received much attention as an alternative energy source for fossil fuels. The biodiesel refers to fuels having physical properties similar to those of light oil, which can be produced by processing plant-derived resources, such as vegetable oil such as rapeseed oil, soybean oil, waste cooking oil, and brown rice oil. Since the biodiesel has the same physical characteristics as those of ordinary diesel, it can be used directly in diesel engines currently used, and the emission of pollutants is small.

Such biodiesel is produced through the synthesis reaction of fatty acid methyl esters by transesterification from plant-derived resources. Glycerol, which is a major by - product of this transesterification reaction, is used in the fields of cosmetics, pharmaceuticals, and food, but the amount of glycerol supplied is in excess of that of industrial demand. For this reason, studies have been actively conducted to convert glycerol, which is a by-product of biodiesel, to other high-value-added materials.

Among these, 1,2-propanediol produced by hydrocracking of glycerol is used as a synthesis material for medicines, intermediates for cosmetics, polyester, unsaturated polyester, and as a plasticizer of cellophane, and is a high value-added material .

The conversion of glycerol to 1,2-propanediol proceeds by hydrogenolysis through a catalyst.

However, US Patent No. 5,616,817 discloses that catalysts containing cobalt, copper, manganese, and molybdenum are prepared to convert glycerol to 1,2-propanediol , The proposed reaction conditions require high pressure of 100 to 700 and a high temperature of 180 to 270 DEG C, which requires very severe conditions.

The conversion of glycerol was 58.5%, the propylene glycol selectivity was 85.5%, and the yield of propylene glycol was 50% at 180 ° C and 40 bar, hydrogen flow condition using the noble metal catalyst supported on hydrotalcite. (Korean Patent Application No. 10-2010-0035921)

In the case of using a copper-chromium catalyst having Pd introduced therein, the yield of propylene glycol was 80% at 220 ° C / 60 bar / H ₂ (Korean Patent Application No. 10-2011-0138612).

Recently, a copper-chromium catalyst having a spinel structure has been reported as a catalyst. However, the catalyst has a problem in that it exhibits activity under high hydrogen pressure of 80 bar or more.

Since such a high hydrogen pressure is a great burden on the chemical process, it is difficult to commercialize 1,2-propanediol. Therefore, it is urgent to develop a catalyst exhibiting high activity under low hydrogen pressure.

On the other hand, when copper-chromium catalyst was used as the catalyst, the conversion of glycerol was 99.9% and the selectivity of propylene glycol was 96%, which was higher than that of glycerol in the case of progressing hydrogenation in a gas phase condition not liquid phase (195 ° C, 20 bar, hydrogen / glycerol = 595, LHSV 0.676) It has been reported that it is possible to obtain catalytic activity (Korean Patent No. 10-2007-7000311). However, since the hydrogen / glycerol molar ratio of the glycerol is too high to be 500 or more for the hydrogenation reaction of glycerol, the volume of the reactor becomes large and the cost of hydrogen separation after the reaction increases.

It is an object of the present invention to solve the above-mentioned problems in the process and to provide a catalyst capable of producing 1,2-propanediol in a high yield over a long period of time under a relatively low hydrogen pressure and a hydrogen / glycerol molar ratio as low as 10 or less Development.

The present inventors have found that when a NiO-CuO / SiO ₂ nanocomposite catalyst prepared by adding a small amount of Ni in the reaction of producing propylene glycol by hydrogenolysis of glycerol in the presence of a metal catalyst, / Glycerol ratio and a high initial glycerol concentration of 80 wt% or higher, 1,2-propylene glycol can be produced at a high yield over a long period of time as well as a high glycerol conversion and a high propylene glycol selectivity can be achieved. Respectively.

According to the present invention, in the reaction of producing propylene glycol by hydrogenolysis of glycerol in the presence of a NiO-CuO / SiO ₂ nanocomposite catalyst, a high glycerol conversion and a high propylene glycol selectivity But also propylene glycol can be produced at a high yield over a long period of time.

A first object of the present invention is to provide a process for the production of propylene glycol by hydrogenation of glycerol in the presence of a complex oxide catalyst of nickel, copper and silicon, comprising the steps of:

Preparing a glycerol aqueous solution (step 1);

- pre-treating the composite oxide catalyst (step 2);

Mixing the glycerol aqueous solution with hydrogen gas, injecting the mixture into a reactor filled with a catalyst and reacting the mixture to produce propylene glycol (Step 3); And

- separating the resulting propylene glycol from glycerol and water (step 4).

According to one embodiment, the aforementioned glycerol and hydrogen may be fed at a molar ratio of 10: 1 or less. Step 2 may be carried out at a temperature of 200 to 250 ° C and a pressure of 20 to 40 atm.

According to another embodiment, the SiO ₂ has a particle size of 5 to 50 nm, and the nanocomposite catalyst described above can be used by pretreating under a hydrogen gas flow.

A second object of the present invention is to provide a NiO-CuO / SiO ₂ nanocomposite catalyst which is prepared by coprecipitation from a Ni precursor compound, a Cu precursor compound and SiO ₂ and is used for the production of propylene glycol by hydrogenation of glycerol .

According to one embodiment, the NiO-CuO / SiO ₂ nanocomposite catalyst may have a mixed oxide and a mixed oxide. In the NiO-CuO / SiO ₂ nanocomposite catalyst, the (Ni + Cu) Component is selected from 50 to 90% by weight of the total catalyst in terms of oxide, and the Ni component can be selected from 0.1 to 25% by weight.

The details of other embodiments are included in the following description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and / or features of the present invention and the manner of achieving them will be apparent with reference to the embodiments and drawings described hereinafter. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, The present invention is only defined by the scope of the claims.

In the present invention, propylene glycol may mean 1,2-propylene glycol or 1,3-propylene glycol, and specifically refers to 1,2-propylene glycol.

Hereinafter, a catalyst for hydrogenation reaction of glycerol according to the present invention, a process for producing the same, and a process for producing propylene glycol by hydrogenating glycerol using the catalyst will be described in detail.

One. NiO - CuO / SiO ₂  Nanocomposite catalyst

According to an embodiment of the present invention, the hydrogenation catalyst of glycerol is a nanocomposite catalyst consisting of a small amount of Ni component, copper component and silica and is represented by Ni-Cu / SiO ₂ , more specifically NiO-CuO / SiO ₂ .

The nanocomposite catalysts are Ni, Cu and Si components are employed may be present in the the compound oxide and mixed oxide mixed form, for example, Ni and Cu components to form a composite oxide represented by the NiO-CuO supported on the SiO ₂ particles Or in the form of discrete particles.

The NiO-CuO / SiO ₂ In the nanocomposite catalyst, the content of the (Ni + Cu) component and the Si component is 50 to 90% by weight, specifically 60 to 90% by weight based on the total catalyst, SiO ₂ is used in an amount of 10 to 50 wt.%, Specifically 10 to 40 wt.%, Preferably 15 to 30 wt.%.

According to the present invention, the Ni component is used in a relatively small amount. The Ni component is preferably 0.1 to 25% by weight, more preferably 0.3 to 20% by weight, By weight may be selected from 0.6 to 15% by weight.

When the content of nickel is less than the above range, there is a problem in that the hydrogen adsorption ability by nickel and the spillover effect of hydrogen are insufficient. When the content exceeds the above range, the reaction proceeds excessively, . The catalyst of the present invention may be in the form of a powder or a pellet. There is no limitation on the form of the catalyst of the present invention, but pellet form is preferable for application to a continuous process, and thus pellet form can be used according to a method commonly used in the art.

2. Method for producing catalyst

The NiO-CuO / SiO ₂ nanocomposite catalyst according to the present invention can be prepared by coprecipitation using a NiO precursor, a CuO precursor and silica particles. For example, the NiO precursor and the CuO precursor are dissolved in a solvent in a silica sol Preparing a precursor solution, adding a precursor solution to the silica sol solution, adjusting the pH of the resulting reaction mixture to form a precipitate, aging the precipitate, filtering and drying the aged precipitate, And firing.

The calcined powder type catalyst may be formed by adding an organic or inorganic binder, kneading and extrusion molding.

According to the present invention, the above-mentioned precursor is not particularly limited, but may be selected from the group consisting of carbide, oxide, chloride, nitride, sulfide, sulfate, nitrate, hydrate thereof or anhydride thereof singly or in combination.

The solvent of the precursor is not particularly limited but may be selected from polar or non-polar solvents capable of dissolving the precursor, for example, ethanol, a lower alcohol such as butanol, water, or a mixture thereof have.

The pH adjustment of the reaction mixture may vary depending on the kind of the components contained, but can be performed, for example, by adding an alkali carbonate or an aqueous solution of sodium hydroxide to the metal precursor solution. The alkaline carbonate or sodium hydroxide aqueous solution may be added to the metal precursor solution so that the pH of the metal precursor solution may be 7 to 13. The specific pH value may be within the above range depending on the type and content of the metal component contained in the metal precursor solution Lt; / RTI >

The particle size, formation rate, etc. of the precipitate may vary depending on the concentration of the alkali carbonate or the sodium hydroxide aqueous solution and the addition rate. For example, if the addition rate of the alkali carbonate or sodium hydroxide aqueous solution is too high or the concentration is too high, the size of the precipitate to be formed becomes large and the activity of the catalyst becomes low. On the other hand, if the addition rate of the alkali carbonate or sodium hydroxide solution is too slow or the concentration is too low, the efficiency of the catalyst production may be decreased. Therefore, in order to effectively suppress the above problems, the concentration of the alkali carbonate or sodium hydroxide aqueous solution is set within a range of 0.5 to 3 mol / L, and the alkali carbonate or sodium hydroxide aqueous solution is added at a rate of 0.1 to 10 mL per minute May be added to the metal precursor solution.

Next, when the pH of the reaction mixture reaches a specific value within the range of 9 to 13, the precipitate can be aged. The aging can be carried out at 50 to 90 ° C for 2 to 12 hours so that the precipitation reaction can take place sufficiently. If the aging temperature is too low or too high, it is difficult to form a precipitate having a high catalytic activity. Therefore, the aging temperature can be set to 50 to 100 ° C, preferably 60 to 90 ° C, as described above.

Next, the precipitate is sufficiently washed with distilled water until the aqueous solution of the alkali carbonate or the aqueous solution of sodium hydroxide remaining in the precipitate is completely removed. The washed precipitate is then filtered and dried. The drying is sufficiently carried out at 80 to 200 DEG C until the precipitate is completely dried.

The dried precipitate may then be calcined to remove organic matter remaining in the precipitate and form a suitable alloy phase. The firing may be performed in an air atmosphere or an oxygen atmosphere at a temperature ranging from 400 to 700 ° C. The specific calcination temperature may be determined at a temperature at which an alloy phase exhibiting high catalytic activity can be formed, and may be varied depending on the kind and content of the metal component contained in the formed precipitate. For example, when a metal component such as copper and nickel is fired at 400 to 700 ° C, preferably 500 to 600 ° C, a suitable alloy phase may be formed.

Next, an inorganic or organic binder is added to the calcined catalyst powder, kneaded and extrusion-molded. The inorganic binder may be selected from other inorganic oxides, for example, silica, zirconia, titania, and the organic binder preferably includes at least one selected from organic binder for ceramics including an ether bond. Specific examples of the organic binder include, but are not limited to, PMB-15U, PMB-40H, and MC-40H.

The catalyst powder added with the coupling agent is uniformly mixed using a mixer, and then mixed with distilled water to prepare a kneading form for molding. And then extruded at an appropriate pressure through an extruder to cut at regular intervals to produce a pellet type catalyst.

Next, the completed pellet catalyst is dried. At this time, moisture is removed.

On the other hand, in the case of using an organic binder for extrusion molding, the dried catalyst may be further calcined at a high temperature in order to remove the organic binder which may interfere with the catalytic activity and to increase the strength of the catalyst. At this time, the firing temperature is preferably about 550 DEG C and the time is preferably 6 to 8 hours.

3. Of propylene glycol  Produce

According to the present invention, a process for preparing propylene glycol from glycerol in the presence of a catalyst for hydrocracking reaction comprises the following steps:

(1) preparing an aqueous glycerol solution;

In this step, when the glycerol aqueous solution contains nonvolatile impurities such as salts generated in the biodiesel synthesis process, it is preferable to first remove the glycerol using an evaporator and then supply it to the catalytic reactor in terms of deactivation of the catalyst Do. However, in the case of impurities (methanol, water, etc.) whose boiling point is lower than that of glycerol, it may be supplied to the catalytic reactor together with glycerol. The concentration of glycerol to be finally fed into the catalytic reactor can be generally selected from 10 to 98%, specifically from 20 to 95%, preferably from 30 to 90%.

(2) filling the catalyst in a reactor and reducing the catalyst using H ₂ gas;

At this stage, the reduction temperature may be specifically selected from 250 to 350 占 폚, preferably from 270 to 330 占 폚.

(3) injecting the glycerol aqueous solution and hydrogen gas together and reacting to produce propylene glycol;

Wherein the molar ratio of hydrogen to glycerol is 100: 1 or less; Reaction temperature: 180 to 260 占 폚, specifically 200 to 240 占 폚, preferably 210 to 230 占 폚; The reaction pressure is selected from 15 to 45 bar, specifically 20 to 40 bar, preferably glycerol feed rate: 0.05 to 3 g / h per 1 g of catalyst, specifically 0.1 to 2 g / h, preferably 0.2 to 1.8 g / h .

- Separation of the resulting propylene glycol from glycerol and water, for example by distillation, extraction and the like.

At this time, if the catalyst of the present invention is molded into a predetermined form such as pellets, it can be helpful to carry out the above production method continuously.

The reaction conditions described above are not critical and can be changed as appropriate. According to an aspect of the present invention, the molar ratio of hydrogen to glycerol is 50 to 1 or less, preferably 20 to 1 or less, and in some cases, 10 to 1 or less, .

One of the characteristics of the present invention is that the glycerol can be kept in a liquid state by suitably controlling the temperature and pressure of the hydrogenation reaction and catalytic hydrogenation can be carried out in a liquid phase by bringing the glycerol into contact with the catalyst and hydrogen, It is possible to prevent the disadvantages and problems associated with the catalytic reaction and to prevent the problems such as coking which is necessarily accompanied by the vapor phase catalytic reaction to a great extent.

Hereinafter, the present invention will be further described on the basis of embodiments, and is not limited in any way by the embodiments.

Example  One: NiO (One)- CuO (79) - SiO2  Hydrogenation of glycerol using nanocomposite catalyst

3.48 g of colloidal silica sol (Ludox SM-30, 30% by weight) was added to 500 ml of distilled water, and while maintaining the temperature at 4 캜, 12.50 g of Cu (NO ₃ ) ₂ .3H ₂ O and 0.19 g of Ni (NO ₃ ) ₂揃 6H ₂ O is slowly added under stirring and mixed. 0.1 N NaOH was added slowly with stirring until the pH of the resulting reaction mixture became 9.2, and then maintained at room temperature for 12 hours, followed by reaction at 75 占 폚 with stirring for 5 hours to form a precipitate.

The reaction mixture was cooled to room temperature and filtered to recover the precipitate. The precipitate was washed with 1000 ml of distilled water until no Na ion was detected, and dried at 100 ° C for 12 hours to obtain the precipitate in powder form.

The obtained powder was calcined at 550 DEG C for 5 hours in an air atmosphere to prepare a nanocomposite catalyst.

1.0 g of the NiO (1) - CuO (79) -SiO ₂ nanocomposite catalyst prepared in the above step was placed in a fixed bed reactor, treated with 10% H ₂ gas at 290 ° C. for 5 hours, 80% glycerol aqueous solution was supplied at a flow rate, and hydrogen was supplied at a flow rate of 16 cc / min. At this time, the temperature of the reactor was maintained at 220 캜 and 30 atm. The reaction was carried out under the above conditions for 300 hours, and the product was analyzed by gas chromatography. The results are shown in Table 1 below.

Example  2: NiO (3) - CuO (77) - SiO ₂  Hydrogenation of glycerol using nanocomposite catalyst

Except that 12.50 g of Cu (NO ₃ ) ₂ .3H ₂ O, 0.63 g of Ni (NO ₃ ) ₂ .6H ₂ O and 3.56 g of colloidal silica were used, Nanocomposite catalysts were prepared. Hydrogenation of glycerol was carried out under the same conditions and conditions as in Example 1 for 300 hours and the product was analyzed by gas chromatography. The results are shown in Table 1 below.

Example  3: NiO (5) - CuO (75) - SiO ₂  Hydrogenation of glycerol using nanocomposite catalyst

Except that 12.50 g of Cu (NO ₃ ) ₂ .3H ₂ O, 1.05 g of Ni (NO ₃ ) ₂ .6H ₂ O and 3.66 g of colloidal silica were used, Nanocomposite catalysts were prepared. Hydrogenation of glycerol was carried out under the same conditions and conditions as in Example 1 for 300 hours and the product was analyzed by gas chromatography. The results are shown in Table 1 below.

Example  4: NiO (10) - CuO (70) - SiO ₂  Hydrogenation of glycerol using nanocomposite catalyst

The procedure of Example 1 was repeated, except that 12.50 g of Cu (NO ₃ ) ₂ .3H ₂ O, 2.29 g of Ni (NO ₃ ) ₂ .6H ₂ O and 3.92 g of colloidal silica were used, Nanocomposite catalysts were prepared. Hydrogenation of glycerol was carried out under the same conditions and conditions as in Example 1 for 300 hours and the product was analyzed by gas chromatography. The results are shown in Table 1 below.

Comparative Example  One: CuO (10) - SiO ₂  Hydrogenation of glycerol using nanocomposite catalyst

The nanocomposite catalyst was prepared in the same manner as in Example 1 except that Ni precursor was not used, 12.50 g of Cu (NO ₃ ) ₂ .3H ₂ O and 3.43 g of colloidal silica were used. Hydrogenation of glycerol was carried out under the same conditions and conditions as in Example 1 for 300 hours, and the product was analyzed by gas chromatography. The results are shown in Table 1 below.

Comparative Example  2: CuO (80) - SiO2  Hydrogenation of glycerol using nanocomposite catalyst

The nanocomposite catalyst was prepared in the same manner as in Example 1, except that Ni precursor was not used and 1.25 g of Cu (NO ₃ ) ₂ .3H ₂ O and 5.50 g of colloidal silica were used. Hydrogenation of glycerol was carried out under the same conditions and conditions as in Example 1 for 300 hours, and the product was analyzed by gas chromatography. The results are shown in Table 1 below.

Comparative Example  3: 2 CuO - Cr ₂ O ₃  Hydrogenation of glycerol using complex oxide catalysts

Except that 4.5 g of Cu (NO ₃ ) ₂ .3H ₂ O and 9.1 g of Cr (NO ₃ ) ₃ .9H ₂ O were used so that the molar ratio of copper and chromium atoms in the catalyst was 1: The same procedures as in Example 1 were carried out to prepare the composite oxide catalyst. Hydrogenation of glycerol was carried out under the same conditions and conditions as in Example 1 for 300 hours, and the product was analyzed by gas chromatography. The results are shown in Table 1 below.

Comparative Example  4: CuO - Cr ₂ O ₃  Hydrogenation of glycerol using complex oxide catalysts

Except that 2.3 g of Cu (NO ₃ ) ₂ .3H ₂ O and 9.1 g of Cr (NO ₃ ) ₃ .9H ₂ O were used so that the molar ratio of copper and chromium atoms in the catalyst was 1: 2 The same procedures as in Example 1 were carried out to prepare the composite oxide catalyst. Hydrogenation of glycerol was carried out under the same conditions and conditions as in Example 1 for 300 hours, and the product was analyzed by gas chromatography. The results are shown in Table 1 below.

Comparative Example  5: PdO (3) - CuO - Cr ₂ O ₃  Hydrogenation of glycerol using complex oxide catalysts

2.3 g of Cu (NO ₃ ) ₂ .3H ₂ O and 9.1 g of Cr (NO ₃ ) ₃ .9H ₂ O were used so that the molar ratio of copper and chromium atoms in the catalyst was 1: 2 and 0.24 g of PdCl ₂ was added to prepare a composite oxide catalyst. Hydrogenation of glycerol was carried out under the same conditions and conditions as in Example 1 for 300 hours, and the product was analyzed by gas chromatography. The results are shown in Table 1 below.

Example catalyst After 30 hours of reaction After 300 hours of reaction Glycerol
Conversion Rate
(%) Propylene glycol
Selectivity
(%) Glycerol conversion (%) Propylene glycol
Selectivity
(%) Example 1 Ni (1) -Cu (79) / SiO ₂ 100 90 100 90 Example 2 Ni (3) -Cu (77) / SiO ₂ 100 96 100 96 Example 3 Ni (5) -Cu (75) / SiO ₂ 100 92 100 92 Example 4 Ni (10) -Cu (70) / SiO ₂ 100 91 100 91 Comparative Example 1 Cu (10) / SiO ₂ 99 74 75 80 Comparative Example 2 Cu (80) / SiO ₂ 99 80 99 80 Comparative Example 3 2CuO-Cr ₂ O ₃ 95 88 65 90 Comparative Example 4 CuO-Cr ₂ O ₃ 100 93 90 94 Comparative Example 5 Pd (3) -CuO-Cr ₂ O ₃ 82 87 69 95

Referring to Table 1,

As shown in Comparative Examples 1 and 2, as the Cu content increases in the Cu / SiO ₂ catalyst not containing the Ni component, the propylene glycol selectivity and the stability of the catalyst are increased, but the propylene glycol selectivity is still not satisfactory ;

As shown in Comparative Examples 3 and 4, in the case of commercially available Cu Chromite (2CuO-Cr ₂ O ₂ or CuO-Cr ₂ O ₃ ), the initial glycerol conversion and propylene glycol selectivity were excellent, but after 200 hours, the glycerol conversion rate Can be seen;

As in Comparative Example 5, even in the case of the Pd-introduced Cu Chromite catalyst, the initial glycerol conversion was also low under the condition that the hydrogen / glycerol ratio was as low as 10 or less, and the reactivity also decreased sharply after 200 hours;

On the other hand, when 1 to 10% by weight of nickel is added to the copper-silica nanocomposite catalyst as in Examples 1 to 4, it can be seen that high glycerol conversion and high propylene glycol selectivity are maintained even after 200 hours of reaction.

Claims (10)

A process for preparing propylene glycol by hydrogenation of glycerol in the presence of a complex oxide catalyst of nickel, copper and silicon, comprising the steps of:
Preparing a glycerol aqueous solution (step 1);
- pre-treating the composite oxide catalyst (step 2);
- injecting the glycerol aqueous solution and hydrogen gas into a reactor filled with a catalyst and reacting to produce 1,2-propylene glycol (step 3); And
Separating the resulting 1,2-propylene glycol from glycerol and water (step 4),
The composite oxide catalyst of nickel, copper and silicon described above is a NiO-CuO / SiO ₂ nanocomposite catalyst prepared from a Ni precursor compound, a Cu precursor compound and SiO ₂ by coprecipitation, and the Ni component is converted into an oxide 0.1 to 25% by weight of the catalyst. The process for producing propylene glycol according to claim 1, wherein the NiO-CuO / SiO ₂ nanocomposite catalyst has a mixed oxide and a mixed oxide. The process according to claim 2, wherein the (Ni + Cu) component in the NiO-CuO / SiO ₂ nanocomposite catalyst is 50 to 90% by weight of the total catalyst in terms of oxides. A process for producing propylene glycol. The process according to claim 1, wherein the Ni component in the NiO-CuO / SiO ₂ nanocomposite catalyst is 0.6 to 15% by weight of the total catalyst in terms of oxides, the production of propylene glycol by hydrogenation of glycerol Way. The process for producing propylene glycol according to claim 1, wherein the glycerol and hydrogen are fed at a molar ratio of 10: 1 or less. 2. The process according to claim 1, wherein step 2 is a pretreatment of a nanocomposite catalyst of nickel, copper and silicon under a hydrogen gas flow. The process according to claim 1, wherein step 3 is carried out at a temperature of from 200 to 250 ° C and a pressure of from 20 to 40 atmospheres. The method of claim 2, wherein the SiO ₂ is a method of producing propylene glycol according to, hydrogenation of glycerol, characterized in that the particle size of the colloidal silica is selected from 5 ~ 50 nm. NiO-CuO / SiO ₂ nanocomposite catalysts prepared by coprecipitation from Ni precursor compounds, Cu precursor compounds and SiO ₂ and used for the production of propylene glycol by hydrogenation of glycerol. 10. The method of claim 9, (Ni + Cu) component and in terms of the oxide 50 to 90% by weight of the total catalyst, of, NiO-CuO / SiO ₂ The Ni component in terms of oxide 0.1 to 25% by weight of the total catalyst Nanocomposite catalysts.